In the processing of a substrate, e.g., a semiconductor substrate (or wafer) or a glass panel such as one used in flat panel display manufacturing, plasma is often employed. During substrate processing, the substrate (or wafer) is divided into a plurality of dies, or rectangular areas. Each of the plurality of dies will become an integrated circuit. The substrate is then processed in a series of steps in which materials are selectively removed (or etched) and deposited.
Copper is becoming the conductor of choice for device interconnects for many integrated circuit manufacturers due to its lower resistivity, better electromigration and stress-void resistance than aluminum. One method of forming a copper interconnect structure employs an electroplating process. In a typical copper electroplating process, a barrier layer of tantalum (Ta) and/or tantalum nitride (TaN) is first deposited over the substrate. Next, a copper seed layer is formed over the barrier layer. Copper seed layer can be deposited by a variety of techniques, including chemical vapor deposition (CVD) and physical vapor deposition (PVD). The substrate is then placed in a bath of an electrolyte plating solution to deposit a copper layer, which is sometimes gap-fill layer, over the copper seed layer.
After plating is completed, the substrate is typically transferred to a rinsing station where a solution including de-ionized water is applied to remove and neutralize any excess or remaining plating solution on the substrate. During the plating process, unwanted copper plating may occur on the bevel edge and/or backside of the substrate, which would become sources of particles. Removal of unwanted copper plating on the substrate backside is relatively straightforward. However, removal of unwanted copper plating on the bevel edge is more challenging.
In view of the foregoing, there is a need for apparatus and methods that provide improved mechanisms of removal of unwanted deposits on the bevel edge to improve process yield.